scholarly journals Drought and flood occurrences in the Lancang River Basin during the last 60 years: their variations and teleconnections with monsoons

2019 ◽  
Vol 11 (4) ◽  
pp. 1798-1810
Author(s):  
Jian Tang ◽  
Huiqun Cao

Abstract Understanding the inconsistency in the effects of monsoon changes on drought and flood occurrences would allow scientists to identify useful indicators in the prediction and early warning of regional drought and flood. Based on the calculation of the Standardized Precipitation Index, monsoon indices, and water vapor fluxes from 1956 to 2015, the relationships between drought–flood occurrences and monsoons in different regions of the Lancang River Basin were investigated. Drought and flood occurrences had spatial differences. Areas located in the lower basin had high drought and flood occurrences. The frequencies of drought and flood occurrences have no obvious regional differences and mainly varied periodically at 3–5, 8–15, and 20–25 years. Because the impact and strength of the Tibetan Plateau Monsoon (TPM) and South Asian monsoon (SAM) are limited, the TPM and SAM are the key factors that affect the occurrences of drought and flood in the upstream and downstream regions of the Lancang River Basin, respectively. The TPM and SAM are potentially useful indicators in the prediction of drought and flood occurrences. These results are of great scientific merit in developing an effective mitigation strategy to reduce the impacts of drought–flood disasters in the Lancang River Basin.

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3501
Author(s):  
Hao Liu ◽  
Zheng Wang ◽  
Guangxing Ji ◽  
Yanlin Yue

Based on the Lancang River Basin (LRB) hydro–meteorological data from 1961 to 2015, this study uses the Mann–Kendall trend test and mutation test to analyze the trend of hydro–meteorological variables, as well as which year the runoff series changes, respectively. We applied the Choudhury–Yang equation to calculate the climate and catchment landscape elasticity of runoff. Then we quantified the impact of climate change and human activities on runoff change. The results show that: (1) the mean annual precipitation (P) in LRB showed an insignificant decline, the annual potential evapotranspiration (E0) showed a significant increase, and the runoff depth (R) showed a significant decrease; (2) the abrupt change of the R occurred in 2005. Both the climate and catchment landscape elasticity of runoff increased, which means that the hydrological process of LRB became more sensitive to climate changes and human activities; (3) compared with the base period (1961–2004), the reduction of P was the leading cause of runoff reduction, with a contribution of 45.64%. The contribution of E0 and human activities to runoff changes are 13.91% and 40.45%, respectively.


2019 ◽  
Vol 50 (3) ◽  
pp. 901-914 ◽  
Author(s):  
Hsin-Fu Yeh

Abstract Numerous drought index assessment methods have been developed to investigate droughts. This study proposes a more comprehensive assessment method integrating two drought indices. The Standardized Precipitation Index (SPI) and the Streamflow Drought Index (SDI) are employed to establish an integrated drought assessment method to study the trends and characteristics of droughts in southern Taiwan. The overall SPI and SDI values and the spatial and temporal distributions of droughts within a given year (November to October) revealed consistent general trends. Major droughts occurred in the periods of 1979–1980, 1992–1993, 1994–1995, and 2001–2003. According to the results of the Mann–Kendall trend test and the Theil–Sen estimator analysis, the streamflow data from the Sandimen gauging station in the Ailiao River Basin showed a 30% decrease, suggesting increasing aridity between 1964 and 2003. Hence, in terms of water resources management, special attention should be given to the Ailiao River Basin. The integrated analysis showed different types of droughts occurring in different seasons, and the results are in good agreement with the climatic characteristics of southern Taiwan. This study suggests that droughts cannot be explained fully by the application of a single drought index. Integrated analysis using multiple indices is required.


2018 ◽  
Vol 49 (6) ◽  
pp. 2002-2015 ◽  
Author(s):  
Zhaoli Wang ◽  
Jiachao Chen ◽  
Chengguang Lai ◽  
Ruida Zhong ◽  
Xiaohong Chen ◽  
...  

Abstract To evaluate the accuracy and applicability of the TMPA 3B42-V7 precipitation product for the Lancang River basin, we used different statistical indices to explore the performance of the product in comparison to gauge data. Then, we performed a hydrologic simulation using the Variable Infiltration Capacity (VIC) hydrological model with two scenarios (Scenario I: streamflow simulation using gauge-calibrated parameters; Scenario II: streamflow simulation using 3B42-V7-recalibrated parameters) to verify the applicability of the product. The results of the precipitation analysis show good accuracy of the V7 precipitation data. The accuracy increases with the increase of both space and time scales, while time scale increases cause a stronger effect. The satellite can accurately measure most of the precipitation but tends to misidentify non-precipitation events as light precipitation events (<1 mm/day). The results of the hydrologic simulation show that the VIC hydrological model has good applicability for the Lancang River basin. However, 3B42-V7 data did not perform as well under Scenario I with the lowest Nash–Sutcliffe coefficient of efficiency (NSCE) of 0.42; Scenario II suggests that the error drops significantly and the NSCE increases to 0.70 or beyond. In addition, the simulation accuracy increases with increased temporal scale.


2020 ◽  
Vol 11 (S1) ◽  
pp. 115-132 ◽  
Author(s):  
M. A. Jincy Rose ◽  
N. R. Chithra

Abstract Temperature is an indispensable parameter of climate that triggers evapotranspiration and has vital importance in aggravating drought severity. This paper analyses the existence and persistence of drought conditions which are said to prevail in a tropical river basin which was once perennial. Past observed data and future climate projections of precipitation and temperature were used for this purpose. The assessment and projection of this study employ the Standardized Precipitation Evapotranspiration Index (SPEI) compared with that of the Standardized Precipitation Index (SPI). The results indicate the existence of drought in the past and the drought conditions that may persist in the future according to RCP 4.5 and 8.5 scenarios. The past drought years identified in the study were compared with the drought declared years in the state and were found to be matching. The evaluation of the future scenarios unveils the occurrence of drought in the basin ranging from mild to extreme conditions. It has been noted that the number of moderate and severe drought months has increased based on SPEI compared to SPI, indicating the importance of temperature in drought studies. The study can be considered as a plausible scientific remark helpful in risk management and application decisions.


2019 ◽  
Vol 29 (1) ◽  
pp. 37-57 ◽  
Author(s):  
Xiongpeng Tang ◽  
Jianyun Zhang ◽  
Guoqing Wang ◽  
Qinli Yang ◽  
Yanqing Yang ◽  
...  

2019 ◽  
Vol 11 (4) ◽  
pp. 1323-1338 ◽  
Author(s):  
Modeste Meliho ◽  
Abdellatif Khattabi ◽  
Guy Jobbins ◽  
Fathallah Sghir

Abstract Located in the mid-west of Morocco, the Tensift watershed shelters the Takerkoust dam, which provides a part of the water used for irrigation of the N'fis agricultural area, which is an important irrigated area of the Tensift watershed. This study deals with the impact of droughts on water inflows to the Takerkoust dam and how the water shortage caused by droughts affects agricultural production in the N'Fis area. The standardized precipitation index (SPI) was used to illustrate the temporal evolution of drought periods. The trend observed on data showed that the Tensift watershed experienced a succession of droughts and humid periods of varying intensities. Periods of drought have negatively affected water inflows to the Takerkoust dam, and therefore the amount of water allocated to agricultural irrigation. Years that experienced droughts showed a restriction of more than 50% of water volume planned for irrigation. During periods of water scarcity, farmers reduce or completely avoid irrigation of annual crops to save water for irrigation of perennial crops. The water shortage for irrigation has led in some cases to a drop of up to 100% of the surface allocated to the production of annual crops.


2014 ◽  
Vol 5 (3) ◽  
pp. 253-262 ◽  
Author(s):  
Fan Na ◽  
Xie Gaodi ◽  
Li Wenhua ◽  
Zhang Yajing ◽  
Zhang Changshun ◽  
...  

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